Conventionally, there is a wireless power feeding technique in which an electric power transmitting unit having an electric power transmitting coil transmits electric power to an electric power receiving unit having an electric power receiving coil in a contactless manner to charge an electric power receiving target.
Among electric power transmitters used in wireless power feeding, there is an electric power transmitter which has a plurality of electric power transmitting units so that electric power can be transmitted to a plurality of electric power receiving targets at the same time.
Further, in the electric power transmitter used in wireless power feeding, a foreign matter on an electric power transmitting unit is detected based on an electric parameter of a circuit so as to prevent electric power from being transmitted in a state where a foreign matter such as a metal is put between an electric power transmitting unit and an electric power receiving unit.
However, when, in the conventional electric power transmitter having a plurality of electric power transmitting units, the electric power transmitter is provided so that one electric power receiving target is placed across the plurality of electric power transmitting units, an electric power transmitting unit located below an electric power receiving unit detects the electric power receiving unit. However, when part of the electric power receiving target is placed above the electric power transmitting units, other electric power transmitting units do not detect the electric power receiving unit, thus detect the electric power receiving target as a foreign matter.
When the electric power transmitter detects a foreign matter, the electric power transmitter issues an alarm to a user through LED lighting, or the like, which results in wasting power consumption of the electric power transmitter due to LED lighting, or the like, and which requires an extra work for a user to halt power feeding and place the electric power receiving target again.